1. Field of the Invention
The present invention relates to the field of spinal fusion devices, and more particularly, relates to spinal fusion devices having an internal bone compacting unit which applies internal compression to fusion materials in order to impart spinal fusion across two or more vertebral bodies.
2. Description of the Related Art
Intervertebral fusion of the spine is a commonly used procedure to join two or more vertebrae. Fusing of the spine is used to eliminate the pain caused by abnormal motion of the vertebrae by immobilizing the faulty vertebrae themselves, which is usually caused by degenerative conditions. Intervertebral fusion is also the preferred way to treat most spinal deformities, specifically scoliosis and kyphosis.
Cage devices are commonly employed to impart spinal fusion across two or more vertebral bodies. Cage devices are often shaped like a ring with or without stabilization mechanisms such as screws, blades, or wings. Cancellous bone or other graft materials are placed within the cage to effect a fusion across two or more vertebral bodies. In some instances, partial healing of the fusion mass occurs perhaps due to partial resorption of the cancellous bone, lack of a compressive force across the fusion space, and/or a loss of the cancellous bone during insertion of the cage on the superior, and/or inferior surfaces of the cage.